1. Field of the Invention
The invention relates to an image forming apparatus using an electrophotographic process, such as a printer, a facsimile and the like.
2. Description of Related Art
There has been know an electrophotographic image forming apparatus in which an electrostatic latent image is formed on a photosensitive drum and then developed with toner to form a toner image on the photosensitive drum.
In general, a development roller for developing the electrostatic latent image is comprised of a metal shaft with a semiconducting elastic layer formed on the circumferential surface of the shaft (see Japanese Patent Application Laid-Open No. 09-31331, for example). As higher speed image forming apparatus became required, a development roller having a high-resistance elastic layer has been used to improve toner charging rate during the developing process, recently.